Volumetric rotary machine

ABSTRACT

A fluid flow displacement rotary machine is provided which includes a casing including an inclined rib on an inner surface thereof, and a shaft provided coaxially with the casing such that the shaft and the casing are rotatable with respect to each other. A disk is mounted to the shaft and includes a recess that is engageable with the rib to divide the space and such that the disk rotates about the axis thereof when the shaft moves with respect to the casing. The recess only engages with the rib at first and second rib contacting portions. The first rib contacting portion is provided at an intersection of the first end face of the disk and the first side surface of the recess, and the second rib contacting portion is provided at an intersection of the second end face of the disk and the second side surface of the recess.

TECHNICAL FIELD

The present invention relates to mechanical engineering, in particular,to fluid-flow positive displacement rotary machines (hereinafterreferred to as DRM (displacement rotary machines) having rotatableworking members, and can find application in internal combustion engines(ICE) including diesel engines, in externally powered engines,compressors, pumps, turbines, as well as in measuring equipment, such asflowmeters and dosimeters.

BACKGROUND ART

Known in the art are DRM having translationally rotatable workingmembers, wherein working chambers communicate with the discharge areaafter precompression occurs, e.g., compressors comprising a casingaccommodating spur-gear rotors at least one of which has its teethprovided with grooves, while the teeth of the other rotor haveprojections mating said grooves (cf., e.g., U.S. Pat. No. 3,535,060,U.S. Pat. No. 4,457,680, U.S. Pat. No. 4,224,016).

Known in the art are also spur rotary compressors available fromIngersoll-Rand Company and having the following constructionarrangement: drive is obtained from a master gear to the gears of thetwo-stage shafts arranged in a V-shaped manner; two compressor rotorspur-gear stages; an intake port disposed in the end covers and partlyon a cylindrical boring of the casing; discharge ports are provided inthe end covers; the discharge port is closed by the end face of aspecially shaped rotor in the course of a compression stroke; the end ofan internal (built-in) compression is fixed by opening the dischargeport by the end face of one of the rotors (cf., e.g., “Resume of scienceand technology”, series “Pump and Compressor Building. RefrigeratingMachinery Building” by P. I. Plastinin and T. M. Kalnin vol. 3, Moscow,VINITI 1986, pp. 83–85).

The above technical solutions suffer from the following disadvantages:

-   -   the DRM under consideration is not a versatile one due to its        not being efficient as a compressor because communication        between the shut-off space and the discharge area is established        without precompression between the rotors. It is not also        applicable as an ICE;    -   the DRM is not a compact one, since only a part of the sealing        disk (i.e., a single tooth) is in action at every instant of        time whereas the remainder part of the machine adds to the        overall dimensions thereof;    -   the peripheral portion of the sealing disk contacts the central        screw portion, and vice versa, which deteriorates the contact        conditions and adds to friction effective therebetween, thereby        affecting the efficiency and service life of the machine.

The most pertinent to the present invention prior art is a DRMcomprising a stator having a concentric effective area, and a main(driving) rotor. Said stator and said main rotor define at least onechamber-defining space there between. The DRM further comprises at leastone driven rotor rotatable about its own axis which overlaps with thedrive rotor axis, said driven rotor being partially deepened in a groovepassing through the stator effective area and having at least one recessmade across the perimeter thereof, said driven rotor dividing said atleast one chamber-defining space into working chambers; inlet and outletports for the working fluid to pass, said ports being disposed in fluidcommunication with the working chambers. The DRM is made as a screw pumpcomprising a housing, a drive screw, and a toothed rotary sealing diskengaging with the screw. The disk teeth are engaged with the recessesdefined between the screw ridges so as to provide a sealed contacttherebetween. The teeth of the sealing disk have parallel side surfaces,triangular-shaped clearances being provided between said teeth.

The threaded screw portion is in its part formed as a shoulder or ridgewhich has a dimension in the direction of the screw rotation such thatit corresponds to the screw displacement while moving the sealing diskfrom a position at which sealing is provided by one of the disk teeth,to a position at which sealing is provided by the next disk tooth (cf.USSR Inventor's Certificate No. 757,770).

SUMMARY OF THE INVENTION

Therefore the object of the present invention is to provide a versatilerotor machine free from a ballast volume (that is, the volume of thestructural members of said inventive machine is determined only bystrength of materials), less sensitive to abrasive impurities in theworking fluid, allowing use of efficient sealing members (of the type oflabyrinth ones), and high-efficiency sealing rings. In addition, it isexpedient to completely release the driven rotor from the momentumdeveloped by the working fluid on the axis of rotor rotation, whichfacilitates synchronization of said rotor with the drive rotor andreduces wear on both.

Said object is achieved by a fluid-flow positive displacement rotarymachine comprising a stator having a concentric effective area and adrive rotor, said stator and said drive rotor defining at least onechamber-defining space therebetween, at least one driven rotor in theform of a disk serving as a piston, said disk being rotatable about itsown axis which is offset from the drive rotor axis, said disk partiallyextending in a groove provided in the stator and having at least onerecess in the periphery thereof, said disk dividing said at least onechamber-defining space into working chambers; inlet and outlet ports forpassing a working fluid, said ports being disposed for fluidcommunication with the working chambers, wherein the chamber-definingspace is defined by a surface body of a revolution around the stator ofthe disk whereby the rotor can rotate around the axis of the stator withsimultaneous rotation of the disk around its own axis, and the followingrelationship is obeyed:

where

-   p is the number of recesses in the disk,-   D is the number of the disk revolutions around its own axis,-   R is the number of the revolutions of the rotor around its own axis-   N is a positive integer,    and the recess arranged in the disk has such a depth at which the    bottom of said recess is within the stator in any position assumed    by said rotor, and each side face of said recess has at least one    drive rotor contacting portion extending along the depth of the

Moreover, in order to increase the effective volume of the workingchambers and reduce the volume of the machine the stator is providedwith a circular ridge wherein the axle of the disk is disposed, thusadding to the specific characteristics of the present DRM.

To use the present DRM as a compressor or an internal combustion engine,the stator is made in the form of a ring having a circular ridge on itsinner surface on which the axle of the disk is supported, whereby aprocess of compression-expansion of the working fluid is carried out byusing a torus geometry.

For a better attachment of the disk axle (since heavy-duty bearings maybe used) said axle extends beyond the said circular ridge which alsoprovides a possibility of establishing additional (external)synchronization of the drive rotor and the disks.

According to one of the embodiments of the present invention, the rotoris fixed, whereas the stator is rotatable around its own axis. Therebyan “external” fluid tightness is improved, i.e., working fluid leakageinto the surrounding environment is reduced. In some instances such anarrangement allows improved internal leak-proofness due to separation ofthe inlet, outlet, and the working chambers by recessless portions ofthe disk.

To simplify the shape of the drive rotor and create a constant torqueapplied to the disk on the part of the working fluid, a drive rotorcontacting portion on at least one side face of the recess is made inthe form of a rib interconnecting the end face of the disk and the sideface of the recess.

To reduce or to eliminate the torque applied to the disk on the part ofthe working fluid, a second drive rotor contacting portion is made inthe form of a second rib disposed on the opposite side face of therecess, the first and the second ribs being situated on one of the diskend faces in order to establish a subtorque applied to the disk on thepart of the working fluid, a second drive rotor contacting portion ismade in the form of a second rib disposed on the opposite side face ofsaid recess, the first and the second ribs being situated on theopposite end faces of the disk, whereby a compensation for friction inthe driven rotor axis is achieved and the shape of the drive rotor andthat of the recess in the disk are simplified.

Depending upon the operating conditions of the DRM and preset parametersof the working fluid, the inlet and outlet ports are disposed on thestator and/or the drive rotor, which is caused by a necessity to reducethe intrinsic hydraulic drag of the DRM.

In particular, when taking the working fluid from the surroundingenvironment the inlet ports are disposed on the stator and drive rotor,and when discharging the working fluid into the surrounding atmospherethe outlet ports are situated on the stator and drive rotor.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is further illustrated by the accompanyingdrawings, wherein:

FIG. 1 is a front view of a fluid-flow positive displacement rotarymachine (DRM) made in the form of a pump having a single disk;

FIG. 2 is a perspective view of a DRM in the form of an internalcombustion engine (ICE);

FIG. 3 shows how the surface of the chamber-defining spaces is formed;

FIG. 4 is a view of a DRM comprising a stationary fixed casing providedwith ports, and two alternately operating disks;

FIG. 5 is a view of a DRM comprising two disks and a stationary shaftprovided with ports;

FIG. 6 is a horizontally sectional view taken along a horizontal line ofFIG. 5;

FIG. 7 is a developed view of a toroidal section in the DRM of FIG. 5;

FIGS. 8 and 9 are perspective partial views of the disk showingdifferently provided recesses across the periphery thereof;

FIG. 10 is a perspective view of a DRM wherein to provide a powertransmitting through the shaft (axis), the working fluid is fed throughthe rotating drive rotor, and two disks with a large overlap areprovided;

FIG. 11 is a view of a DRM in the form of a compressor;

FIG. 12 is a top view of the compressor of FIG. 11;

FIG. 13 is a developed view of the toroidal section illustratingoperation of a DRM in the form of a compressor comprising a single disk;and

FIG. 14 is a developed view of the toroidal section illustratingoperation of the DRM of FIG. 10.

BEST METHOD OF CARRYING OUT THE INVENTION

With reference to FIG. 1 the DRM comprises a shaft 1 serving as a statorhaving a concentric effective area 2 consisting of a surface 3 of acircular ridge, said surface being connected to surfaces of cylindricalportions 4 and 5 which in turn communicate with a working fluid inletmanifold 6 and a working fluid outlet manifold 7, a casing 8 serving asa drive rotor whose wall 9 has two circular ridges 10 defining a groove11 for a belt drive (not shown).

Between the casing 8 (rotor) and the shaft 1 (stator) threechamber-defining spaces 12 are formed separated from one another by ribs13 of the casing 8. As seen in FIG. 1, the rib 13 is inclined andseparates the inlet and outlet in the direction of rotation of therotor. Surfaces 14 of the chamber-defining spaces 12 are formed byeffective areas 15 of the ribs 13, by a concentric inner surface 16 ofthe wall 9, and by the concentric surface 2 of the shaft 1. Thechamber-defining spaces 12 are subdivided into working chambers 17 by adisk 18 serving as a piston, the disk 18 being rotatable around its ownaxle 19. FIG. 2 depicts four disks 18 serving as pistons. The axle 19 ofeach of said disks is offset from an axis 20 of the shaft 1. The disk 18is partially inserted in a groove 21 in shaft 1 and projects into thechamber-defining space. Each of the disks 18 has at least one recess 22arranged at the periphery of the disk for engaging the rib 13.

FIG. 3 shows the disks each with four such recesses. The shaft 1(stator) and/or the casing 8 (rotor) is provided with a working fluidinlet port 23 and a working fluid outlet port 24, said ports beingadapted to get into fluid communication with the working chambers 17.

FIG. 1 shows the working fluid inlet port 23 disposed in the statorcylindrical portion 4. The chamber-defining space 12 is defined by thesurface 14 similar to the surface of a body formed by rotating the shaft1 together with the disk 18 around the axis 20 of shaft 1 simultaneouslywith rotation of the disk 18 around its own axle 19. When defining thesurface 14 of the chamber-defining space 12 the following relationshipis obeyed:

$\frac{p \cdot D}{R} = N$

where:

-   -   p is the number of recesses 22 in the disk,    -   D is the number of revolutions of the disk around its own axis,    -   R is the number of revolutions of the rotor with respect to the        stator, and    -   N is a positive integer.

In addition, the numerical values of the quantities p, D, and R areselected depending on operating conditions of the DRM.

The recess 22 (FIG. 8) arranged at the periphery of the disk 18 has sucha depth that a bottom 25 of said recess 22 is situated within the shaft1 (stator) in any position assumed by said disk 18, and each side face26 of said recess 22 (FIG. 3) has at least one contacting portion 27 ofthe side surface 26, said portion 27 extends along a depth of the recess22.

FIG. 6 illustrates a fluid-flow positive displacement rotary machinewherein the shaft 1 has a circular outer surface 3 and the axle 19(axis) of the disk 18 is disposed in the shaft 1.

FIG. 2 illustrates a fluid-flow positive displacement rotary machinewherein the casing is made in the form of a ring 28 having a circularridge 3 on the internal surface thereof, the axle 19 of the disk beingsituated inside said circular ridge 3.

FIG. 2 depicts a fluid-flow positive displacement rotary machine,wherein an extension 29 of the axle 19 of the disk 18 protrudes beyondthe limits of the circular ridge 3.

FIG. 4 shows a fluid-flow positive displacement rotary machine, whereinthe casing 8 is stationary and serves as the stator, while the shaft 1is rotatable around its own axis 30 and serves as the rotor. There areprovided two disks 18 which are additionally synchronized with eachother and each has a recess 22.

FIGS. 5 and 6 illustrate a fluid-flow positive displacement rotarymachine, wherein the drive rotor 8 is fixed stationary, while the stator1 is rotatable around its own axis 30. There are provided two drivenrotors 18 overlapping each other and having six recesses each.

FIG. 7 presents a developed view of a toroidal section illustratingoperation of the DEM according to FIGS. 5 and 6. In this particular casethe DRM is crossed by the surface of a torus whose axis of symmetryaligns with the axis of the shaft 1 and the axial circumference of whichtouches the axes of the disks 18. A radius R_(T) of section of saidtorus is equal to the section radius R_(R) of the disk 18. In saiddeveloped view two lateral lines 18A represent the same disk 18, and thecenter line 18B denotes the other disk 18. The slanting lines 13A denotethe ribs 13 between which the chamber-defining spaces 12 are formed. Thechamber-defining spaces 12 are subdivided into the working chambers 17by the disks 18. The dotted lines indicate the working fluid inlet andoutlet ports 23A and 24A.

FIGS. 5 and 6 illustrate a fluid-flow positive displacement rotarymachine, wherein the casing 8 is fixed stationary, while the shaft 1 isrotatable around its own axis 30. There are provided two disks 18overlapping each other and having six recesses 22 each.

FIG. 8 shows the recess 22 in the disk 18 of the DRM. It is the rib ABof the side face 26 (ABCD) of the recess 22 that is in fact the driverotor contacting portion 27, said rib interconnecting the disk end face31 with the side face 26 of the recess 22. In this particular case asecond contacting portion on the other side face A′B′C′D′ of the recess22 is in fact the rib A′B′ formed at intersection of the side faceA′B′C′D′ of the recess 22 with the disk end face on which the edge AB isdisposed.

FIG. 9 also shows a recess 22 in the disk 18 of the DRM. It is the ribAB of the side face 26 (ABCD) of the recess 22 that is in fact the diskcontacting portion 27, said rib interconnecting the disk end face 31with the side face 26 of the recess 22. A second disk contacting portionis made in the form of the rib C′D′ disposed on the opposite side faceA′B′C′D′ of the recess, the ribs being disposed on the opposite endfaces 31 of the disk.

FIG. 1 represents the arrangement of the working fluid inlet ports 23 onthe shaft 1 of a DRM. FIG. 4 represents the arrangement of the workingfluid inlet ports 23 on the casing 8 of a DRM. Arrangement of theworking fluid inlet ports 23 both on the shaft 1 and the casing 8 is notshown in the drawings. Arrangement of the working fluid outlet ports 24on the shaft 1 of a DRM is shown in FIG. 1 and their arrangement on thecasing 8, in FIG. 4. Whenever it becomes necessary, the outlet ports 24are arranged both on the shaft 1 and the casing 8 (not shown).

An alternative embodiment of the inventive DRM as a pump is depicted inFIG. 10, wherein the shape of the surface 3 on the shaft 1 isapproximately spherical. The disk 18 protrudes from the shaft 1 into theworking chambers by about one-third (as for the angular dimensionthereof) of its overall length, which improves the pump specificcharacteristics irrespective of whether the torque is transmitted via ashaft, a belt transmission or a gearing. In cases where the torque istransmitted via a shaft, the working fluid is fed under a low pressurethrough the wall 9 of casing 8. Thus a constructional arrangement isrealized, wherein a high-pressure tube for withdrawing the working fluidis accommodated inside a low-pressure tube for feeding the working fluid(not shown). In this case leaks due to loose spots from high-pressuretube get into the low-pressure tube.

One more embodiment of the present invention is a compressor shown inFIG. 11, wherein the disk 18 is made integral with its axle 19. The diskthickness diminishes towards its periphery. The disk has three radialrecesses 22 spaced apart symmetrically at the periphery thereof. Thesurface 3 of the shaft 1 is torus-shaped. The ring 28 of the shaft 1 isa breadthwise fragment of a hollow torus which is complemented to a fulltorus by the wall 9 of casing 8. Three symmetrically arrangedchamber-defining spaces 12 are interposed between casing 8 and the shaft1. Low-pressure working fluid is fed through the inlet manifold 6 shapedas a tube inside which an outlet manifold 7 is accommodated. The outletmanifold 7 is made in the form of a tube for withdrawing high-pressureworking fluid.

To increase compression ratio of the compressor without affecting thedimension of the outlet port 24 use is made for an effect of reducingthe dimensions of the working chambers by their having from the torusouter side to the inner side thereof. To further increase thecompression ratio, the outlet ports 24 adjacent to the disk 18 havesmaller angular dimensions than the inlet port 23 (which is well seen onFIG. 12) adjacent to the disk 18 on the opposite side. Drive is effectedthrough a shaft.

FIG. 13 shows a developed view of the toroidal section illustratingoperation of the DRM made in the form of a pump having a single disk.This view differs from the developed view shown in FIG. 7 in the angleof slope of the ribs 13 and in that only one disk 18 is shown thereinand accordingly there are half as many inlet and outlet ports. Moreover,the inlet ports 23 and the outlet ports 24 occupy only part of theangular dimension of the shaft 1. When comparing the developed viewsshown in FIGS. 7 and 13, one can take notice of a difference in thedegree of loading of the disks, i.e., a variable-magnitude andreversible but partly compensated for cocking moment presented in thedeveloped view of FIG. 7 and a constant moment shown in the developedview of FIG. 13.

The developed view of a toroidal section of FIG. 14, which illustratesoperation of the DRM made in the form of a pump shown in FIG. 10,differs from the developed view of FIG. 13 by the provision of two disks18 which leads to another angle of slope of the ribs 13.

The fluid-flow positive displacement rotary machine of the presentinvention operates as follows.

Now the operation of a DRM made in the form of a pump (FIG. 1) and adeveloped view of the toroidal section through said pump (FIG. 13) willhereinafter be considered. Sections (edges) of the development pass onthe disk (vertical edge) and on the circular surface 3 (horizontaledge). Three constant-volume chamber-defining spaces 12 are formed bythe shaft 1 (stator) and the casing 8 (rotor). While operating (i.e.,rotating from the drive) the disk 18 subdivides the three spaces 12 (andsometimes two of said spaces 12) into chambers whose volume increases asthe casing 8 rotates, and which communicate with the working fluid inlet23 port, and into chambers having a volume decreasing as the casing 8rotates and which communicate with the working fluid outlet port 24. Itis a feature of such arrangement that during a part of the working cyclethe chamber-defining space 12 is free from the disk 18 and said space 12communicates neither with the working fluid inlet port 23 nor with theworking fluid outlet port 24.

Now referring to a fluid-flow positive displacement rotary machine madein the form of a higher fluid-tightness pump (FIG. 4), a singlechamber-defining space 12 is formed by the rotary shaft 1 and thestationary-fixed casing 8, said space 12 having itsconstant-cross-sectional area portion which is continuously covered by arecess-free portion of one of the disks 18, and the working fluid isforced to flow along said portion from the working fluid inlet port 23to the working fluid outlet port 24. Rotation of two disks 18 issynchronized so that at least one of them engages with the casing 8. Itis a feature of such arrangement that the different-pressure chambersare separated from each other by the recess-free portion of the disk 18,which makes it possible to low quality requirements imposed on thesurface of the recess 22.

Operation of the DRM made in the form of a pump having a shaft 1 servingas the rotor, a casing B serving as the stator, and two disks 18overlapping each other (FIG. 5) is illustrated by a developed view ofthe toroidal section thereof (FIG. 7). Three constant-volumechamber-defining spaces 12 are defined by the shaft 1 and the casing 8,said spaces communicating the working fluid inlet ports 23 with theworking fluid outlet ports 24. The disks 18 subdivide said spaces 12into the chambers whose volume increases as the shaft 1 rotates withrespect to the casing 8 rotates and which are in fluid communicationwith the working fluid inlet port 23, and into the chambers having theirvolume decreasing as the shaft 1 rotates with respect to the casing 8and which communicate with the working fluid outlet port 24.

Operation of the DRM made in the form of a shaft-driven pump (FIG. 10,wherein the shaft is not shown) is illustrated by a developed view ofthe toroidal section thereof (FIG. 14). Three constant-volumechamber-defining spaces 12 are defined by the shaft 1 and the casing 8.The disks 18 subdivide said spaces 12 into the chambers whose volumeincreases as the shaft 1 rotates with respect to the casing 8, and whichare in fluid communication with the working fluid inlet port 23, andinto the chambers whose volume decreases as the shaft 1 rotates withrespect to the casing 8, and which are in fluid communication with theworking fluid outlet port 24.

It is a feature of such arrangement that the boundary line between thehigh and the low pressures lies on one of the end faces 31 of the disk18, whereby the load on said rotor becomes constant which in turn makesit possible to mount the disk 18 in the shaft using a hydrostaticbearing.

Operation of the DRM made in the form of a compressor (FIG. 11) is asfollows. Three constant-volume chanter-defining spaces 12 are defined bythe shaft 1 and the casing 8. The disk 18 subdivides the three spaces 12(and sometimes two of said spaces 12) into chambers whose volumeincreases as the casing 8 rotates, and which communicate with theworking fluid inlet port 23, and into chambers having a volumedecreasing as the casing 8 rotates and which communicate with theworking fluid outlet port 24 only after precompression of the workingfluid. All the chambers pass all the phases per one drive rotorrevolution, that is, (i) an increase of the volume from zero to maximumupon being brought into communication with the working fluid inlet port23 (suction stroke), (ii) a decrease of the volume down to minimumwithout communication with the ports 23, 24 (compression stroke), and(iii) decreasing the volume down to zero upon being brought intocommunication with the working fluid outlet port 24 (exhaust stroke).

The present fluid-flow positive displacement rotary machine shown inFIG. 2 may be used as a diesel engine. It proceeds as follow. With therotors rotating, the volume of the chambers defined by the shaft 1,casing 8, and disk 18 is increased and said chambers are filled with afuel-air mixture through the working fluid inlet ports 23. Once thevolume of said chambers has reached a local maximum, communicationbetween the chambers and the working fluid inlet port 23 ceases. As saidchambers approximate the axis of symmetry of the DRM, the volume ofchambers starts decreasing due to a change in the configuration thereof.Any compression ratio is attainable by selecting ratio between thedimensions of the casing 8 and of the disks 18, as well as between thethickness thereof. When the chambers are arranged symmetrically withrespect to the plane of axes of the disks 18, the compression ratio ismaximized, whereby the fuel-air mixture ignites. Further on, as thechambers move away from the axis of the DRM symmetry the volume of thechambers increases. A second local maximum of the chambers' volumeexceeds the first one due to different dimensions of the ports and mayfurther be increased when the surface 3 is out-of-symmetry with respectto the plane of the axes of the disks 18, whereby each chamber may bebrought in communication with the working fluid outlet (exhaust) ports24 at a pressure equal to atmospheric one. When continuous-action sparkplugs and fuel injectors are mounted in the stator recesses (not shown),a liquid-fuel internal combustion engine results.

INDUSTRIAL APPLICABILITY

A pilot model of a pump, according to the invention, was manufacturedfrom aluminum. Routine testing of the model at the Leningradmetal-working plant in St. Petersburg were carried out successfully andconfirmed its serviceability. The aforementioned advantages of theproposed invention and a wide range of materials, including ceramics,from which the herein-proposed pumps, compressors, and the rotor-typeinternal combustion engines may be manufactured (since a single kind ofmotion performed by the component parts of fluid-flow positivedisplacement rotary machines is their uniform rotation around stationaryfixed axles, which reduces loads on the parts of the DRM), as well ashigh specific output at the same rotational speed thereof compared withother rotor-type machines, all this testifies a possibility of efficientuse of the present invention both on industrial scale and in technology,including aircraft engineering and the automotive industry, especiallywhen the engines of such type are disposed in the wheels of a motorvehicle.

1. A fluid flow displacement rotary machine comprising: a casingincluding a first portion comprising an inclined rib formed in an innersurface thereof and a second portion without the inclined rib, saidsecond portion being distinct from said first portion and being adjacentto said first portion along a circumferential direction of the casing; ashaft provided coaxially with the casing, said shaft and said casingbeing rotatable with respect to each other; a space defined by the innersurface of the casing and an outer surface of the shaft; a fluid inletand a fluid outlet communicating with said space; two rotatable disks,each of the two disks including a recess that is engageable with theinclined rib, and being rotatably mounted on the shaft, wherein theshaft includes two grooves therein, each of which houses a portion of acorresponding disk and has a depth such that a bottom of the recess isalways within the groove in the shaft, and wherein rotation of said twodisks around respective axes thereof is synchronized with respect toeach other; wherein when the shaft and the casing rotate with respect toeach other, the two disks are moved with the shaft with respect to thecasing, and a first disk of the two disks moves across the secondportion to push fluid while the recess of the first disk is positionedwithin the corresponding groove in the shaft; and wherein while thefirst disk moves through the second portion of the casing, the recess ofa second disk of the two disks engages with the inclined rib such thatthe second disk rotates about the axis thereof, and the first disk isrotated about the axis thereof synchronously with the second disk as thetwo disks move with the shaft.
 2. The fluid flow machine of claim 1,wherein the shaft comprises a circular ridge on the outer surfacethereof.
 3. The fluid flow machine of claim 2, wherein an axle of eachof the two disks is mounted in the circular ridge.
 4. The fluid flowmachine of claim 3, wherein a part of the axle extends out from thecircular ridge.
 5. The fluid flow machine of claim 1, wherein the casingis stationarily fixed and the shaft is rotatable about the axis thereof.6. The fluid flow machine of claim 5, wherein the inlet port and theoutlet port are provided in the casing.
 7. The fluid flow machine ofclaim 1, wherein the shaft is stationary and the casing is rotatable. 8.The fluid flow machine of claim 7, wherein the inlet port and the outletport are provided in the shaft.